1. Field of the Invention
This invention relates to a method of cutting and removing a nuclear reactor for dismantling and removing a used nuclear reactor.
2. Description of the Prior Art
Generally, nuclear reactors reach a permanent operation termination period 30 to 40 years after the start of the operation. Even after a nuclear fuel is withdrawn, a nuclear reactor has residual radioactivity such as radioactivation products, and various regulations have been put in force to ensure safety management and disposal for decommissioning of such a nuclear reactor.
Means for decommissioning a nuclear reactor comes in three types. First means closes a nuclear reactor facility and puts it under suitable management, second means executes work such as shielding of the nuclear reactor to tightly isolate radioactive materials form outside and third means dismantles and removes radioactive structures inside the reactor facility.
Since only a limited environment for installation of the nuclear reactor is available, a new facility, too, is preferably set up inside the same facility as the existing facility and in this sense, the third means for dismantling and removing the used reactor is preferred among the means described above. Accordingly, the development of a method of dismantling and removing safely and efficiently the used reactor has been earnestly desired.
As means for accomplishing the object described above, a method has been proposed which cuts vertically and horizontally the body base portion of the reactor, for example, by continuous core boring so as to cut off the base portion from a pressure vessel, and transports and preserves them under a sealed state in a large waste preservation warehouse.